Greenspace: Fertilizers becoming more environmentally friendly

A few fertilizer makers, sensing coming state and federal regulation, are reformulating their products to almost eliminate phosphorus. Our fish and aquatic animals applaud us.

Jim Hillibish

This is the year of the zero in some lawn and garden fertilizer. Our fish and aquatic animals applaud us.

A few fertilizer makers, sensing coming state and federal regulation, are reformulating their products to almost eliminate phosphorus. You will see it in the three-number nutrient indicator on packages, for nitrogen, phosphorus and potassium. These are the three major nutrients all plants need.

I recently bought Scott’s lawn fertilizer, and the middle phosphorus number is zero.

Some states, especially those with large wetlands areas or along the coasts, already have banned high-phosphorus fertilizer. The problem starts with something we all have, run-off water.

When it rains, some of the water rolls off our properties and into storm sewers or drainage ditches. If we’ve fertilized, some of the nutrients will be in the water.

Phosphorus was in high strength in fertilizer to promote new plant growth.

All drainage water heads for streams, and when phosphorus reaches them, it creates wild aquatic plant growth, including algae.

Soon, the stream stagnates with this green stuff, all pulling oxygen out of the water. This drives away the fish and other waterborne creatures and suffocates the ones that stay, causing fish kills on hot summer days.

Phosphorus is in fertilizer because it is a good starter for plants. If you’ve planted a new lawn, high-phosphorus fertilizer often is recommended to jumpstart the turf.

The zero-phosphorus fertilizers do not mean the fertilizer will be less effective. Soil in many areas is naturally high in phosphorus.

Low amounts of phosphorus will be greeted happily by plants that love high-acid soils.

These include pine and fir trees, azaleas and rhododendrons. Excessive amounts of phosphorus can stunt or kill these plants.

Most lawn fertilizer is applied with broadcast spreaders. You’ll note that the instructions on the new packages warn to avoid spreading fertilizer on sidewalks and drives. That’s because it will run off directly, full strength.

It’s difficult to control a broadcast spreader. You probably will need to sweep the excess fertilizer onto the lawn. This is why fertilizer now comes in bright colors to make the broadcast path apparent.

It makes sense to be careful. You won’t waste fertilizer and you won’t have chemical stains on pavements.